w6qhs - yagi failures
ERIC.L.SCACE at adn.sprint.com
ERIC.L.SCACE at adn.sprint.com
Mon Jun 13 12:33:30 EDT 1994
Hi Dave --
Sorry, lost the original message with your internet address...
My experience has been with KLM KT34XA:
1. bent elements from ice loading:
cause: weak point in element design is one foot from butt of element,
where an inner strengthening tube (I think it is 3/4") section
stops.
fix: replace inner section with longer section; I used 6' sections that
I had lying around.
2. boom failure at boom-mast plate, front half
cause: massive wind loading after > 1" radial ice load. wind speeds above
60 mph. boom collapsed sideways, ripped off.
fix: probably requires trusses with a sideways component to them, rather
than a simple overhead truss
in the same storm :
3. elements fell off:
cause: hose clamps which fasten element mounting backet around the boom
snapped thru the bands due to horizontal windload on iced element.
fix: none possible with current design.
and finally:
4. strap which taps T-match and the element end loading section to the main
tube of the element slipped off.
cause: collision of element with the ground
solution: install antenna in free space
-- Eric K3NA
p.s.: oh yeah -- their turnbuckles for the overhead guy will rust. replace
with galvanized units.
The KT34XA is also not wind-balanced. Move antenna at least a foot to rear
and add counterbalancing weight inside boom.
>From es at mvuss.att.com (Edward S Parsons +1 508 960 6722) Mon Jun 13 16:55:00 1994
From: es at mvuss.att.com (Edward S Parsons +1 508 960 6722) (Edward S Parsons +1 508 960 6722)
Date: 13 Jun 94 15:55:00 GMT
Subject: VHF Scores, Issue 2
Message-ID: <9406131557.AA01916 at ig1.att.att.com>
Jun 1994 ARRL VHF Contest Early Scores, Issue 2
--------------------------------------------------
Please send any additional scores. K1TR @ K1XX or Internet: es at mvuss.att.com
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
S/O:
BAND WA2TEO K1RZ KA1ZE K9MK
------ ------- ------ ------- ------- ----- ----- ----- ------
50MHz 202/55 162/53 62/23 214/96
144 344/41 281/44 415/41 166/34
220 82/29 65/26 79/28 6/3
432 124/35 103/30 134/34 67/22
903 21/15 17/13 16/11 2/2
1.2 31/14 34/16 32/13 13/7
2.3 5/3 5/3
3.4 3/2
------------------------------------------------------------------------------
TOTAL 809/192 662/182 746/155 468/164
216k 169k 167k 94k
BAND N1DPM K3ZO K1ZZ W2IOG/3 KO0U/4 KC5BQS
------ ------- ------ ------- ------- ----- ----- ----- ------
50MHz 43/22 194/69 106/24 45/19 3/2
144 98/27 273/42 175/24 132/38 93/25 14/7
220 52/21 3/2 38/21
432 69/23 55/17 33/17 47/17 5/2
903 11/8 4/3
1.2 28/12 2/2 11/8 10/4 2/1
2.3 8/5
3.4 4/3
------------------------------------------------------------------------------
TOTAL 313/121 467/111 341/69 214/84 195/65 28/15
66k 52k 28k 26k 17k 675
QRP-Portable:
BAND KH6CP/1
------ ------- ------ ------- ------- ----- ----- -----
50MHz 47/15
144 111/20
220 54/17
432 71/15
903 14/8
1.2GHz 22/9
2.3 5/4
3.4 4/3
5.6 6/4
10 3/3
-----------------------------------------------------------------------
TOTAL 337/98
57k
Rover:
BAND N5RZ(+K5MR) NG0X NJ2L
------ ------- ------ ------- ------- ----- ----- ----- ------
50MHz 206/120 66/34 19/12
144 168/89 80/38 16/14
220 15/12
432 64/42 34/21 12/9
903 4/4
1.2 22/17 5/4
------------------------------------------------------------------------------
TOTAL 460/268 214/93 71/55
152k 20k 6.4k
Limited/Multioperator:
BAND K1TR/3 K3MQH W3EP/4 K3UA W5KFT KB5KYJ WW1M/9 WD0T
------ ------- ------ ------- ------- ----- ----- ----- -----
50MHz 440/86 383/78 480/135 378/98 472/194 148/71 48/27 29/23
144 756/50 707/57 280/55 571/64 126/28 54/22 57/21
220 140/35 142/36 95/44 82/36 21/13
432 262/38 242/41 105/39 93/37 41/17 13/8 16/6
1.2 16/10
----------------------------------------------------------------------------
TOTAL 1598/210 1474/212 960/273 1124/235 655/249 215/101 142/67 29/23
418k 394k 316k 305k 181k 23k 12k 667
Multioperator/Unlimited:
BAND W2SZ N2WK W3ZZ W4IY W0UC W3XO/5
------ ------- ------ ------- ------- ----- ----- -----
50MHz 395/70 293/92 380/106 307/83 214/100 311/146
144 594/52 428/64 433/57 358/59 273/66 71/19
220 159/33 180/47 84/33 59/26 55/30 3/3
432 284/40 221/47 171/39 143/32 91/35 21/12
903 58/21 77/32 22/16 14/8 3/3 3/2
1.2GHz 91/24 86/29 78/18 30/13 21/13 5/3
2.3 53/17 46/23 1/1
3.4 41/10 17/14
5.6 30/7 9/7
10 41/7 16/3 5/1
24 19/7
144G 1/1
-----------------------------------------------------------------------
TOTAL 1766/289 1379/360 1153/273 916/222 658/248 414/185
885k 860k 426k 271k 212k 84k
>From eric%modular.UUCP at cs.arizona.edu (Eric Gustafson) Mon Jun 13 16:46:39 1994
From: eric%modular.UUCP at cs.arizona.edu (Eric Gustafson) (Eric Gustafson)
Date: Mon, 13 Jun 94 08:46:39 MST
Subject: Antenna Question
Message-ID: <9406131546.AA25671 at modular>
Randy,
I haven't done any modeling to confirm the claim. As of right now I'm
highly skeptical. But... _IF_ the addition of a parallel unconnected wire
had the effect of raising the radiation resistance significantly, then the
losses in the ground connection (usually between a 12 and 25 ohm connection
for a single ground rod) would become a much lower fraction of the total
resistance in the circuit and the effeciency would be increased. A single
element 1/4 wave vertical has a radiation resistance of about 36 ohms. so
with a (lucky) 12 ohm ground rod, it would be very close to a 50 ohm system
at resonance (and the efficiency would be close to 75% to begin with). I
guess I'll have to look at the article to see what is actually being
proposed. To have only a 20 percent efficiency, would require the antenna
to have only 3 ohms of radiation resistance (again assuming our lucky 12
ohm ground rod).
An efficiency increase (as I read this statement) from 20 to 60 percent
means to me:
1. Originally the efficiency was 20 percent
2. Now it is 60 percent
3. I can now (with the same power input to the system) expect my signal to
be almost 5 dB (about 1 S-unit) louder than it was when the efficiency
was 20 percent.
73 Eric N7CL
------------------------------------------------------------------------------
Eric Gustafson N7CL | The mountains are high and the Emperor
6730 S. Old Spanish Trail | is far away.
Tucson, AZ 85747 |
INTERNET: modular!eric at cs.arizona.edu | You can't work 'em
CI$: 71750,2133 | if you can't hear 'em.
------------------------------------------------------------------------------
>From Jim Reisert AD1C 13-Jun-1994 1213 <reisert at wrksys.enet.dec.com> Mon Jun 13 17:46:06 1994
From: Jim Reisert AD1C 13-Jun-1994 1213 <reisert at wrksys.enet.dec.com> (Jim Reisert AD1C 13-Jun-1994 1213)
Date: Mon, 13 Jun 94 12:46:06 EDT
Subject: Recent VHF/UHF ARRL 'test (de N4MM)
Message-ID: <9406131646.AA00381 at us4rmc.pko.dec.com>
[Forwarded from YCCC PacketCluster]
Msg #343 From: N4MM Date: 13-Jun 1050Z Subj: RE: Recent VHF/UHF ARRL 'test
I have been receiving comments about some of the poor operating practices
in the recent ARRL June VHF Contest. I participated in the contest some,
but due to other duties I was not on that much. I heard somethings that
were not in the best interest of the contest spirt and carryovers from
HF contests. I received a rash of phone calls back in January when the
ARRL VHF/UHF SS was running. Most of these were due to hogging FM
channels, endlessly.
In order to get action and more awareness of these situations, please write
the CAC, and copy your ARRL Director. The more people who take the time
to do this, the quicker things will happen. If only one or two write,
the problem will not receive the attention that it should. For example:
If only one or two write, chances for any quick positive action are slim,
however if many write, then things will move faster and be taken more
seriously. Ten letters is better than one, 100 letters is better than 10.
73, John, N4MM
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